iommu/vt-d: Enable PCI/IMS

PCI/IMS works like PCI/MSI-X in the remapping. Just add the feature flag,
but only when on real hardware.

Virtualized IOMMUs need additional support, e.g. for PASID.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221124232327.081482253@linutronix.de

drivers/iommu/intel/irq_remapping.c

@@ -82,7 +82,7 @@ static const struct irq_domain_ops intel_ir_domain_ops;
 
 static void iommu_disable_irq_remapping(struct intel_iommu *iommu);
 static int __init parse_ioapics_under_ir(void);
-static const struct msi_parent_ops dmar_msi_parent_ops;
+static const struct msi_parent_ops dmar_msi_parent_ops, virt_dmar_msi_parent_ops;
 
 static bool ir_pre_enabled(struct intel_iommu *iommu)
 {
@@ -577,7 +577,11 @@ static int intel_setup_irq_remapping(struct intel_iommu *iommu)
 
 	irq_domain_update_bus_token(iommu->ir_domain,  DOMAIN_BUS_DMAR);
 	iommu->ir_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT;
-	iommu->ir_domain->msi_parent_ops = &dmar_msi_parent_ops;
+
+	if (cap_caching_mode(iommu->cap))
+		iommu->ir_domain->msi_parent_ops = &virt_dmar_msi_parent_ops;
+	else
+		iommu->ir_domain->msi_parent_ops = &dmar_msi_parent_ops;
 
 	ir_table->base = page_address(pages);
 	ir_table->bitmap = bitmap;
@@ -1429,11 +1433,20 @@ static const struct irq_domain_ops intel_ir_domain_ops = {
 };
 
 static const struct msi_parent_ops dmar_msi_parent_ops = {
-	.supported_flags	= X86_VECTOR_MSI_FLAGS_SUPPORTED | MSI_FLAG_MULTI_PCI_MSI,
+	.supported_flags	= X86_VECTOR_MSI_FLAGS_SUPPORTED |
+				  MSI_FLAG_MULTI_PCI_MSI |
+				  MSI_FLAG_PCI_IMS,
 	.prefix			= "IR-",
 	.init_dev_msi_info	= msi_parent_init_dev_msi_info,
 };
 
+static const struct msi_parent_ops virt_dmar_msi_parent_ops = {
+	.supported_flags	= X86_VECTOR_MSI_FLAGS_SUPPORTED |
+				  MSI_FLAG_MULTI_PCI_MSI,
+	.prefix			= "vIR-",
+	.init_dev_msi_info	= msi_parent_init_dev_msi_info,
+};
+
 /*
  * Support of Interrupt Remapping Unit Hotplug
  */